The present invention relates to an apparatus, system and method of organizing a disordered stream of articles into an ordered stream of single items spaced from each other for subsequent processing.
In high volume product handling operations, such as mail handling and similar processing, large quantities of items such as boxes, parcels packages or parts often varying widely in size, must be inducted into a sorter system. Typically, a feeder system for use in such processing areas takes a disordered stream of items fed to it on a conveyor and inducts the items onto a sorter system. The feeder system ideally should perform several functions. To the maximum extent possible, the feeder should singulate disordered items in order to present the articles to downstream processing equipment, such as a sorter, one at a time with some minimum specified spacing or separation between product items. The feeder system must also provide for the reading of destination information from the item so that the control system for the sort can track it through the system and sort it correctly. In the U.S., scannable bar codes are used for this purpose in automated systems. A third important function is intercepting and removing items which are non-machinable because they are too large, too heavy or the like from the system for special handling.
Singulation is an essential first step in the handling and sorting of product items such as boxes, parcels or soft packages. Material singulation as used herein means the generation of a flow of discrete pieces of material having no two pieces abreast, stacked, or having a gap or lineal (in the direction of flow) separation less than some minimum value. In other words, singulation is a process whereby a randomly input stream of items moving on a conveyor system is separated into a stream of single items spaced from each other so that a downstream process can readily perform operations on each item one at a time. Mixed item streams are a particular challenge in that a mixed material stream may include packages that vary greatly in size and may be piled at random one upon another, forming agglomerates of packages that are difficult to detect and separate.
Presently, singulation is accomplished in two ways, by manual manipulation of material on bulk conveying lines and with mechanical singulators that rely on the mechanical characteristics of the material being singulated to generate an output stream in which the probability that each piece is singulated is high. While manual operations can be relatively effective, they are costly; and high throughput, either continuous or in bursts, can exceed an individual""s capacity, resulting in xe2x80x9cdoublesxe2x80x9d or xe2x80x9cmultiplesxe2x80x9d (unsingulated output). Conventional mechanical singulation schemes vary widely in method, throughput, and error rates, but tend to be large (requiring a large amount of floor space) and subject to high error rates when handling material at the margins of the mechanical material specifications for which they are designed and/or tuned. They too tend to degrade in performance when they encounter heavy bursts of material flow.
According to one previously proposed method for singulation of mail, an inclined ramp with holes for applying suction is provided. Letters are allowed to slide down the ramp and then suction is applied to hold them in place on the slide. The suction is then selectively released in order to release one item at a time. See Interim Report For Phase I, U.S. Postal Service Contract 104230-85-H-0002, Apr. 5, 1985, ElectroCom Automation, Inc.,pages 3-10 to 3-13. This method provide one form of singulation, but is of doubtful utility for larger items that maybe difficult to hold effectively using suction and that may tend to tumble down a slide, possibly evading the effect of suction and leaving the singulator prematurely. The system according to the present invention addresses these difficulties.
The selective advance intelligent singulator of the invention provides a means of generating a stream of single pieces of discrete material, such as cartons, from a single layer bulk flow, accumulation, or batch containing one or more of said pieces. It is used to convert a bulk material flow or batch to a stream of single items with controlled spacing on a conveying device such as may be needed for some process such as reading or sorting. It accomplishes accurate separation of a wide spectrum of pieces using knowledge of material boundaries acquired by various means, computer processing using a straightforward algorithm, and a suitable conveying mechanism to selectively pull material piece-by-piece from a single layered, bulk accumulation of pieces, i.e. with an intelligent process.
In one aspect, the invention provides a singulator including a conveyor for carrying a group of items from an entry end towards an exit end and an item detection system, such as a vision system, that captures image information associated with pieces of material along with the position of the pieces. The singulator includes a mechanism for selectively advancing selected items while retarding the advance of other items so that the forward motion of selected lead items can be controlled independently of the remaining pieces. A control system controls the operation of the conveyor or conveyor(s) and the mechanism for actuating the conveyor or conveyors in a manner effective to remove pieces from a group of pieces one at a time based upon the position of the piece or piece(s) and image information captured by the detection system.
Pieces are advanced in accordance with a removal scheme including the steps of: (1) selecting a first item for removal; (2) actuating one or more conveyors or conveyor sections underlying the selected piece and between the first item and the exit end of the conveyor in order to transport the first item to the exit end of the singulator at a velocity relative to the following pieces sufficient to create a gap between the first piece and the next piece where the following piece may have a velocity between zero and the exit velocity; (c) actuating one or more conveyors or conveyor sections underlying the next piece to be removed and between the next item to be removed and the exit end of the conveyor in order to transport the first item to the exit end of the singulator at a velocity relative to the following pieces sufficient to create a gap between that piece and the following piece; and (d) repeating step (c) for additional items.
A control system utilizes image and item position information derived from the detection system and the removal scheme to control operation of the conveyor and the mechanism for selectively advancing and retarding pieces so that the pieces exit from the singulator one at a time.
The conveyors or conveyor sections may comprise an array of independently controlled rotary carriers such as belts or rollers that allow movement of a velocity boundary across the singulator. The conveyor may also comprise one or more sliding conveyors or conveyor sections with extendable belts that also allow for movement of a velocity boundary across the singulator.
The principle advantage of the selective advance intelligent singulator is its capacity to reliably singulate bulk material in a number of embodiments adaptable to the throughput, material mix, cost, and other requirements of a particular encompassing system design. A selective advance intelligent singulator provides an accurate means of automating the singulation function in a compact machine capable of handling a wide spectrum of material without risk of increased error rates or otherwise degraded performance as flow fluctuates.